The present invention relates to a wheel bearing unit including a rotation speed sensor, preferably including a two row wheel bearing. The invention is useful for automotive vehicles, and particularly vehicles with an ABS/traction control system. There is a pulse generating ring which rotates with the bearing ring and a centrally arranged, rotationally fixed sensor on which the pulse generating ring is mounted.
Such a wheel bearing unit is described in German Patent Application P 42 13 379 of an assignee hereof. In that case, the pulse generating ring is developed as a cup shaped structural part which is rotatably mounted on the housing of the sensor, and it is coupled to the rotating bearing ring by a driver.
This mounting must assure an exact size of the air gap between the pulse generating ring and the sensor in order to exclude erroneous pulses. The sensor comprises, for instance, evaluation electronics and/or signal conversion. The sensor should be so fixed in position with respect to the pulse generating ring that even upon tilting of the ball races when the vehicle travels around curves or as a result of impact upon a wheel due to its striking against a curb, the air gap should change as little as possible and there may be no contact between the pulse ring and the sensor. Oscillations which occur on the wheel must not lead to errors in the measurement or to the development of noise. Further, it should be possible for the sensor to be easily mounted on the wheel bearing. In this connection, defective mounting, whether done by hand on an assembly line or by a mounting robot, must be reliably recognized so that it can be eliminated immediately. Finally, replacement of the sensor should be facilitated.